WO2024034323A1

WO2024034323A1 - Current interruption device and charge/discharge control circuit

Info

Publication number: WO2024034323A1
Application number: PCT/JP2023/025927
Authority: WO
Inventors: 高博公文; 将起吉岡; 孝明鈴間
Original assignee: ボーンズ株式会社
Priority date: 2022-08-10
Filing date: 2023-07-13
Publication date: 2024-02-15
Also published as: JP2024024993A

Abstract

A current interruption device 100 comprises a plurality of breakers 1 having different operation temperatures connected in parallel with each other. The breakers 1 comprise: a fixed piece 2 having a fixed contact 21; a movable piece 4 that includes an elastic portion 44 capable of elastic deformation and a movable contact 41, and that presses the movable contact 41 onto the fixed contact 21 to establish a contact therebetween; and a thermally responsive element 5 that deforms in accordance with a temperature change, to thereby cause transition of the state of the movable piece 4 from a conduction state in which the movable contact 41 is in contact with the fixed contact 21 to an interruption state in which the movable contact 41 is separated from the fixed contact 21.

Description

Current interrupter and charge/discharge control circuit

The present invention relates to a current interrupting device that interrupts current in response to temperature changes.

Conventionally, a device for interrupting current has a fixed contact, a movable piece that presses the movable contact against the fixed contact, and a movable piece that deforms with temperature changes to change the state of the movable piece when the movable contact contacts the fixed contact. A breaker is known that includes a thermally responsive element that causes the movable contact to transition from a conductive state to a disconnected state in which the movable contact is separated from the fixed contact (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2015-079594

The above-mentioned current interrupt device is usually placed near a heat generating element such as a secondary battery or a load, and operates in response to a rise in temperature of the heat generating element to protect the secondary battery and the like. In a circuit including such a current interrupting device and a secondary battery, if the transition of the temperature of the heating element can be detected in detail before the movable piece transitions from the conductive state to the interrupted state and the current is interrupted, for example, , it can be used to control the voltage applied to the load, and the safety of secondary batteries etc. can be further improved.

However, in a current interrupting device configured with a single breaker, it is difficult to detect the temperature of the heating element in detail before the current is interrupted.

The present invention has been devised in view of the above-mentioned circumstances, and an object of the present invention is to provide a current interrupting device capable of detecting in detail the temperature transition of a heating element before the current is interrupted. is the main purpose.

The present invention is a current interrupting device that interrupts current,
a fixed piece having a fixed contact; a movable piece having an elastic part that can be elastically deformed and a movable contact, the movable piece presses the movable contact against the fixed contact to contact the fixed contact; a thermally responsive element that changes the state of the movable piece from the conductive state in which the movable contact contacts the fixed contact to the disconnected state in which the movable contact is separated from the fixed contact; A plurality of breakers having different operating temperatures at which they turn off are connected in parallel.

The current interrupting device of the present invention includes a plurality of breakers that have a fixed piece, a movable piece, and a thermally responsive element, and have different operating temperatures. As the temperature of the heating element rises, the state of the movable pieces of the breakers, starting from the breaker with the lowest operating temperature, changes from the conductive state to the cut-off state. Since each breaker is connected in parallel, the resistance between both ends of the current interrupting device fluctuates as the state of each movable piece changes, and when the state of the movable piece of all breakers changes to the cutoff state, the current is blocked. Therefore, by monitoring the variation in resistance between both ends of the current interrupting device, it is possible to detect in detail the change in temperature of the heating element before the current is interrupted. Therefore, for example, by controlling the input and output of the secondary battery based on the resistance between both ends of the current interrupting device, it is possible to easily improve the safety of the secondary battery and the like.

FIG. 1 is a diagram showing a current interrupting device that is an embodiment of the present invention. FIG. 2 is a perspective view showing the configuration of the breaker in FIG. 1 before assembly. FIG. 3 is a cross-sectional view showing the breaker of FIG. 2 in a conductive state. FIG. 3 is a cross-sectional view showing the breaker of FIG. 2 in a disconnected state. FIG. 2 is a perspective view of another configuration of the breaker in FIG. 1 before assembly; FIG. 6 is a cross-sectional view showing the breaker of FIG. 5 in a conductive state. FIG. 6 is a cross-sectional view showing the breaker of FIG. 5 in a disconnected state. FIG. 2 is a diagram showing the initial operation of the current interrupting device of FIG. 1; FIG. 9 is a diagram illustrating the operation of the current interrupting device in chronological order following FIG. 8 . 10 is a diagram showing the operation of the current interrupting device in chronological order following FIG. 9; FIG. 11 is a diagram showing the operation of the current interrupting device in chronological order following FIG. 10. FIG. FIG. 12 is a diagram showing, in chronological order, the operation of the current interrupting device in which one breaker returns to the conductive state following FIG. 11; FIG. 2 is a block diagram showing a charge/discharge control circuit including the current interrupt device of FIG. 1. FIG.

FIG. 1 shows a current interrupting device 100 that is an embodiment of the present invention. The current interrupting device 100 is a device that interrupts current according to temperature changes. The current interrupting device 100 is configured by connecting a plurality of breakers 1 in parallel.

Terminals

101 and 102 for detecting the resistance between both ends of the current interrupting device 100 are provided at both ends of the current interrupting device 100 of this embodiment. One of the terminals 101 is connected to, for example, the secondary battery pack 201, and the other is connected to, for example, the power supply unit 202 or the load 203 (see FIG. 13, which will be described later).

2 to 7 show the breaker 1. The breaker 1 includes a fixed piece 2 having a fixed contact 21, a movable piece 4 having a movable contact 41 at the tip, a thermally responsive element 5 that deforms with temperature changes, a fixed piece 2, a movable piece 4, and a thermally responsive element 5. It is composed of a case 10 and the like that accommodates the element 5. The case 10 includes a case body (first case) 7, a lid member (second case) 8 attached to the upper surface of the case body 7, and the like.

A terminal 22 exposed from the case 10 is formed on the fixed piece 2. A terminal 42 is formed on the movable piece 4 exposed from the case 10. The breakers 1 are connected in parallel by connecting the

terminals

22 and 42 of each breaker 1 to each other.

The fixing piece 2 is formed, for example, by pressing a plate-shaped metal material whose main component is copper or the like (in addition, a metal plate of copper-titanium alloy, nickel silver, brass, etc.). The fixing piece 2 is embedded in the case body 7 by insert molding and is housed in the case body 7 with the terminal 22 exposed to the outside of the case body 7.

The fixed contact 21 is formed at a position facing the movable contact 41 by cladding, plating, or coating with a highly conductive material such as silver, nickel, nickel-silver alloy, copper-silver alloy, or gold-silver alloy. , is exposed through a part of an opening 73a formed inside the case body 7.

The terminal 22 is formed at one end of the fixed piece 2. The terminal 22 protrudes outward from the side wall at the edge of the case body 7.

In this application, unless otherwise specified, the surface of the fixed piece 2 on which the fixed contact 21 is formed (i.e., the upper surface in FIG. 2) is the first surface, and the opposite surface is the second surface. It is explained as. When the direction from the fixed contact 21 to the movable contact 41 is defined as a first direction, and the direction opposite to the first direction is defined as a second direction, the first surface faces the first direction, and the second surface faces the second direction. Turn in the direction. The same applies to other parts, such as the movable piece 4 and the thermally responsive element 5.

The movable piece 4 is formed into an arm shape symmetrical with respect to the longitudinal centerline by pressing a plate-shaped metal material whose main component is copper or the like.

A movable contact 41 is formed at the tip of the movable piece 4 in the longitudinal direction. The movable contact 41 is made of the same material as the fixed contact 21, for example, and is joined to the tip of the movable piece 4 by welding, cladding, crimping, or other methods.

A terminal 42 is formed at the other end of the movable piece 4 in the longitudinal direction. The terminal 42 protrudes outward from the side wall at the edge of the case body 7. One of the

terminals

22 and 42 is connected to the terminal 101 of the secondary battery, and the other is connected to the terminal 102.

The movable piece 4 has a contact portion 43 and an elastic portion 44 between the movable contact 41 and the terminal 42. The contact portion 43 contacts the case body 7 and the lid member 8 between the terminal 42 and the elastic portion 44 . The contact portion 43 has a protrusion portion 43a that protrudes in the lateral direction of the movable piece 4 in a wing shape. By providing the protruding portion 43a, the contact portion 43 is sandwiched between the case body 7 and the lid member 8 in a wide and large area, and the movable piece 4 is firmly fixed to the case 10.

The elastic part 44 extends from the contact part 43 to the movable contact 41 side. The movable piece 4 is cantilever-supported by the case 10 at the contact portion 43 on the base end side of the elastic portion 44, and is formed at the distal end portion of the elastic portion 44 by elastically deforming the elastic portion 44 in this state. The movable contact 41 is pressed against and comes into contact with the fixed contact 21, and the fixed piece 2 and the movable piece 4 can be energized.

The movable piece 4 is curved or bent at the elastic portion 44 by press working. The degree of curvature or bending is not particularly limited as long as the thermally responsive element 5 can be accommodated, and may be appropriately set in consideration of the elastic force at the operating temperature and return temperature, the pressing force of the movable contact 41, etc. Furthermore, a pair of

protrusions

44a and 44b are formed on the second surface of the elastic portion 44 so as to face the thermally responsive element 5. The protrusion 44a protrudes toward the thermally responsive element 5 on the base end side, and comes into contact with the thermally responsive element 5 in a blocked state. The protrusion 44b protrudes toward the thermally responsive element 5 on the distal end side (that is, on the movable contact 41 side) of the protrusion 44a, and comes into contact with the thermally responsive element 5 in the cut-off state. When the thermally responsive element 5 is deformed due to overheating, the thermally responsive element 5 comes into contact with the

protrusions

44a and 44b, and the deformation of the thermally responsive element 5 is transmitted to the elastic part 44 via the

protrusions

44a and 44b, causing the movable piece 4 to deform. The tip is pushed up (see Figure 4).

The thermally responsive element 5 shifts the state of the movable piece 4 from a conductive state in which the movable contact 41 contacts the fixed contact 21 to a disconnected state in which the movable contact 41 is separated from the fixed contact 21. The thermally responsive element 5 has an initial shape whose cross section is curved into an arc, and is formed into a plate shape by laminating thin plate materials having different coefficients of thermal expansion. When the operating temperature is reached due to overheating, the curved shape of the thermally responsive element 5 is reversely warped with a snap motion, and is restored when the temperature drops below the return temperature due to cooling. The initial shape of the thermally responsive element 5 can be formed by press working. The material and shape of the thermally responsive element 5 are not particularly limited as long as the elastic part 44 of the movable piece 4 is pushed up by the reverse warping action of the thermally responsive element 5 at the desired temperature and returned to its original state by the elastic force of the elastic part 44. However, a rectangular shape is desirable from the viewpoint of productivity and efficiency of the reverse warping operation.

The material for the thermally responsive element 5 is a stack of two types of plate-shaped metal materials with different coefficients of thermal expansion made of various alloys such as nickel silver, brass, and stainless steel, which are used in combination according to the required conditions. be done. For example, as a material for the thermally responsive element 5 that can provide a stable operating temperature and return temperature, a combination of a copper-nickel-manganese alloy on the high expansion side and an iron-nickel alloy on the low expansion side is desirable. Further, from the viewpoint of chemical stability, a more desirable material is a combination of an iron-nickel-chromium alloy on the high expansion side and an iron-nickel alloy on the low expansion side. Furthermore, a more desirable material from the viewpoint of chemical stability and processability is a combination of an iron-nickel-chromium alloy on the high-expansion side and an iron-nickel-cobalt alloy on the low-expansion side.

The operating temperature of the thermally responsive element 5 alone depends on the coefficient of thermal expansion and thickness of the metal constituting the thermally responsive element 5, the curvature of the thermally responsive element 5, and the like. Therefore, by appropriately changing these parameters, a thermally responsive element 5 having a desired operating temperature can be obtained.

The case body 7 and lid member 8 that make up the case 10 are molded from thermoplastic resin such as flame-retardant polyamide, polyphenylene sulfide (PPS) with excellent heat resistance, liquid crystal polymer (LCP), and polybutylene terephthalate (PBT). has been done. Materials other than resins may be used as long as they can provide properties equivalent to or better than those of the resins described above.

A recess 73 is formed in the case body 7, which is an internal space for accommodating the movable piece 4, the thermally responsive element 5, and the like. The recess 73 has

openings

73a and 73b for accommodating the movable piece 4, an opening 73c for accommodating the movable piece 4 and the thermally responsive element 5, and the like. The edges of the movable piece 4 and the thermally responsive element 5 incorporated in the case body 7 are brought into contact with a frame formed inside the recess 73, and are guided when the thermally responsive element 5 is warped in reverse.

A metal plate mainly composed of copper or the like or a metal plate made of stainless steel or the like may be embedded in the lid member 8 by insert molding. The metal plate appropriately contacts the first surface of the movable piece 4 to restrict the movement of the movable piece 4, and also increases the rigidity and strength of the lid member 8 and the case 10 as a casing, while reducing the size of the breaker 1. To contribute.

As shown in FIGS. 2 and 5,

openings

73a, 73b, 73c, etc. of the case body 7 accommodate the fixed piece 2 (fixed contact 21), the movable piece 4 (movable contact 41, elastic part 44), the thermally responsive element 5, etc. A lid member 8 is attached to the case body 7 so as to cover the case body 7. The case body 7 and the lid member 8 are joined by, for example, ultrasonic welding. As a result, the breaker 1 is assembled with the

terminals

22 and 42 exposed.

3, 4, 6, and 7 schematically show the operation of the breaker 1. Figures 3 and 6 show the operation of the breaker 1 in normal charging or discharging conditions. In a normal charging or discharging state, the thermally responsive element 5 maintains its initial shape before being reversely warped. By pressing the movable contact 41 toward the fixed contact 21 by the elastic part 44, the movable contact 41 and the fixed contact 21 come into contact, and the fixed piece 2 and the movable piece 4 of the breaker 1 are brought into a state where they can be electrically connected. Ru.

As shown in FIGS. 3 and 6, the thermally responsive element 5 may be separated from the

protrusions

44a and 44b of the movable piece 4 in the conductive state. This increases the contact pressure between the movable contact 41 and the fixed contact 21, and reduces the contact resistance between them.

4 and 7 show the operation of the breaker 1 in an overcharged state or in an abnormal state. When a high temperature state occurs due to overcharging or an abnormality, the thermally responsive element 5 that has reached the operating temperature is reversely warped and comes into contact with the elastic part 44 of the movable piece 4, and the elastic part 44 is pushed up and the fixed contact 21 and the movable contact 41 are separated. are separated. At this time, the current flowing between the fixed contact 21 and the movable contact 41 is cut off.

When the overcharged state is canceled or the abnormal state is eliminated, the thermally responsive element 5 returns to its recovery temperature and restores its original initial shape. Then, the movable contact 41 and the fixed contact 21 come into contact again due to the elastic force of the elastic portion 44 of the movable piece 4, and the circuit is released from the disconnected state and returns to the conductive state shown in FIGS. 3 and 6.

As shown in FIG. 1, the current interrupting device 100 of the present invention includes a plurality of (three in the figure) breakers 1 having different operating temperatures. The operating temperature of each breaker 1 depends on the operating temperature and elastic modulus of the thermally responsive element 5 alone, the elastic modulus of the movable piece 4, and the like. Therefore, for example, by changing the material, shape, etc. of the thermally responsive element 5, it is possible to adjust the operating temperature of each breaker 1.

Since the current interrupting device 100 includes a plurality of breakers 1 having different operating temperatures, as the temperature of the heating element increases, the state of the movable piece 4 shifts from the conductive state to the cutoff state in order from the breaker 1 with the lowest operating temperature. . Since the breakers 1 are connected in parallel, the resistance between both ends of the current interrupting device 100 changes as the state of each movable piece 4 changes, and the state of the movable piece 4 of all the breakers 1 changes to the cut-off state. The current is cut off when the transition occurs. Therefore, by monitoring the change in resistance between both ends of the current interrupting device 100, it is possible to detect in detail the change in temperature of the heating element before the current is interrupted. Therefore, for example, by controlling the input/output of the secondary battery based on the resistance between both ends of the current interrupting device 100, it is possible to easily improve the safety of the secondary battery, etc.

Note that the resistance between both ends of the current interrupting device 100 is calculated from, for example, the potential difference between the

terminals

101 and 102 and the current flowing through the current interrupting device 100.

In the plurality of breakers 1, it is desirable that the resistance between both ends of at least one breaker 1 in a conductive state is different from the resistance between both ends of the other breakers 1 in a conductive state. The resistance between both ends of each breaker 1 in the conductive state is the sum of the conduction resistance of the fixed piece 2 and the movable piece 4 and the contact resistance between the fixed contact 21 and the movable contact 41. Since the resistance between both ends of at least one breaker 1 in the conductive state is different from the resistance between both ends of the other breakers 1 in the conductive state, the state of the movable piece 4 of the breaker 1 has changed from the conductive state to the cutoff state. It becomes easy to identify the temperature of the heating element, and it becomes possible to detect the temperature transition of the heating element in detail.

The resistance between both ends of each breaker 1 in the conductive state may be different from each other. Since the resistances between both ends of each breaker 1 in the conductive state are different from each other, the breaker 1 in which the state of the movable piece 4 has changed from the conductive state to the cutoff state can be identified, and the transition of the temperature of the heating element can be detected in detail. becomes possible.

In the current interrupting device 100, it is desirable that the breaker 1 includes one or more first breakers 1A. In FIG. 1, a current interrupting device 100 including one first breaker 1A is shown.

2 to 4 show the first breaker 1A. The first breaker 1A includes, in addition to the fixed piece 2, the movable piece 4, the thermally responsive element 5, and the case 10, a PTC (Positive Temperature Coefficient) thermistor 6 that connects the fixed piece 2 and the thermally responsive element 5. .

· The PTC thermistor 6 brings the fixed piece 2 and the movable piece 4 into electrical continuity when the movable piece 4 is in the cutoff state. The PTC thermistor 6 is disposed between the fixed piece 2 and the thermally responsive element 5. That is, the support portion 23 of the fixed piece 2 is located directly below the thermally responsive element 5 with the PTC thermistor 6 in between. When the fixed piece 2 and the movable piece 4 are de-energized by the reverse warping action of the thermally responsive element 5, the current flowing through the PTC thermistor 6 increases. As long as the PTC thermistor 6 is a positive characteristic thermistor whose resistance increases as the temperature rises and limits the current, the type can be selected depending on the operating current, operating voltage, operating temperature, release temperature, etc. The material and shape are not particularly limited as long as these characteristics are not impaired. In this embodiment, a ceramic sintered body containing barium titanate, strontium titanate, or calcium titanate is used. In addition to the ceramic sintered body, a so-called polymer PTC, which is a polymer containing conductive particles such as carbon, may be used.

In the first breaker 1A in the cut-off state shown in FIG. 4, the thermally responsive element 5 comes into contact with the movable piece 4, and a slight leakage current flows through the thermally responsive element 5 and the PTC thermistor 6. That is, the PTC thermistor 6 causes the fixed piece 2 and the movable piece 4 to be electrically connected via the thermally responsive element 5, which causes the movable piece 4 to enter the cutoff state. The PTC thermistor 6 continues to generate heat as long as such leakage current flows, and the resistance value increases dramatically while maintaining the thermally responsive element 5 in a reversely warped state. does not flow, and only the slight leakage current mentioned above exists (constitutes a self-holding circuit). This leakage current can be used for other functions of the circuit including the current interrupt device 100.

In the first breaker 1A, when the movable contact 41 separates from the fixed contact 21, the leakage current flows between the fixed piece 2 and the movable piece 4 via the thermally responsive element 5 and the PTC thermistor 6. Therefore, generation of arc discharge between the fixed contact 21 and the movable contact 41 is suppressed. Therefore, by configuring the plurality of breakers 1 constituting the current interrupting device 100 to include one or more first breakers 1A, arc discharge occurring inside the current interrupting device 100 is suppressed, and the current interrupting device 100 safety is increased.

In the current interrupting device 100, the breaker 1 may include one or more second breakers 1B. When the current interrupting device 100 includes one first breaker 1A, the current interrupting device 100 further includes one or more second breakers 1B. When the number of second breakers 1B included in the current interrupt device 100 is one, the current interrupt device 100 further includes one or more first breakers 1A. In FIG. 1, a current interrupting device 100 including two second breakers 1B is shown.

Figures 5 to 7 show the second breaker 1B. The second breaker 1B is composed of the fixed piece 2, the movable piece 4, the thermally responsive element 5, the case 10, etc., and does not include the PTC thermistor 6 included in the first breaker 1A. The resistance of the second breaker 1B in the cut-off state is substantially infinite.

In the second breaker 1B, the resin constituting the case body is raised in the area where the PTC thermistor 6 was arranged in the first breaker 1A, and the fixed piece 2 and the thermally responsive element 5 are insulated from each other. There is. Such a second breaker 1B is cheaper than the first breaker 1A having the PTC thermistor 6. Therefore, by including the second breaker 1B as the breaker 1 of the current interrupting device 100, the manufacturing cost of the current interrupting device 100 can be suppressed. Furthermore, by including the plurality of second breakers 1B, the manufacturing cost of the current interrupting device 100 can be suppressed.

The current interrupting device 100 shown in FIG. 1 has a single first breaker 1A and two second breakers 1B. Such a current interrupt device 100 can suppress arc discharge during operation while suppressing manufacturing costs. Note that variations of the breaker 1 that constitutes the current interrupting device 100 are not limited to the combination of a single first breaker 1A and two second breakers 1B. For example, the current interrupting device 100 of the present invention may be configured by a combination of a single first breaker 1A and a single second breaker 1B, or may be configured by a plurality of first breakers 1A. . Moreover, the current interrupting device 100 of the present invention may be configured by a combination of a single or plural first breakers 1A and three or more second breakers 1B. In this case, the manufacturing cost of the current interrupting device 100 can be suppressed by configuring the current interrupting device 100 with a larger number of second breakers 1B than the number of first breakers 1A. Note that in applications where particularly low manufacturing costs are required, the current interrupting device 100 may be configured only by the plurality of second breakers 1B.

8 to 11 show in chronological order the operation of the current interrupting device 100 including the first breaker 1A and the second breakers 1B1 and 1B2 when the temperature of the current interrupting device 100 rises. Here, the operating temperature of the second breaker 1B1 is T1, the operating temperature of the second breaker 1B2 is T2, the operating temperature of the first breaker 1A is T3, and T1<T2<T3. Further, the resistance between both ends of the second breaker 1B1 in the conductive state is R1, the resistance between both ends of the second breaker 1B2 in the conductive state is R2, the resistance between both ends of the first breaker 1A in the conductive state is R3, The resistance between both ends of the first breaker 1A in the cut-off state is R0.

In the following, it is assumed that the temperature difference between the first breaker 1A and the second breakers 1B1 and 1B2 is small, and the temperatures of the first breaker 1A and the second breakers 1B1 and 1B2 are substantially equal to the temperature of the heating element.

As shown in FIG. 8, in the initial state where the temperature of the heating element is lower than T1, the first breaker 1A and the second breakers 1B1 and 1B2 all maintain a conductive state, and the resistance between both ends of the current interrupting device 100 is RR1 is represented by the combined resistance of the first breaker 1A and the second breakers 1B1 and 1B2.

As shown in FIG. 9, when the temperature of the heating element reaches T1, the second breaker 1B1 shifts to the cutoff state, and the resistance RR2 between both ends of the current interrupting device 100 changes between the first breaker 1A and the second breaker 1B2. It is expressed as the combined resistance of

As shown in FIG. 10, when the temperature of the heating element reaches T2, the second breaker 1B2 shifts to the cutoff state, and the resistance RR3 across the current interrupting device 100 is expressed by the resistance of the first breaker 1A. Ru.

Then, as shown in FIG. 11, when the temperature of the heating element reaches T3, the first breaker 1A shifts to the cutoff state, and the resistance RR4 across the current interrupting device 100 changes to the cutoff state of the first breaker 1A. It is represented by the resistance R0 at . In addition, in the current interrupting device 100, when all the breakers 1 are comprised of the 2nd breaker 1B which does not include the PTC thermistor 6, resistance RR4 becomes infinite.

As shown in FIGS. 8 to 11, the resistance across the current interrupting device 100 changes depending on the temperature of the heating element. Therefore, by monitoring the resistance across the current interrupting device 100, it is possible to know the temperature of the heating element.

Normally, the resistance of each breaker 1 when the movable piece 4 is in a conductive state is extremely small, and the resistance of each breaker 1 when the movable piece 4 is in a disconnected state is extremely large. Therefore, when any of the breakers 1 transitions to the conductive state, the variation in resistance between both ends of the current interrupting device 100 is not so large. Therefore, in this embodiment, by setting the resistance between both ends of each breaker in the conductive state as follows, the fluctuation of the resistance between both ends of the current interrupting device 100 is increased, and the detection accuracy of the operation of each breaker is increased. be enhanced.

In the current interrupting device 100, the resistance R3 between both ends of the first breaker 1A in a conductive state is equal to the resistance R1 between both ends of the second breaker 1B1 in a conductive state and the resistance between both ends of the second breaker 1B2 in a conductive state. It is desirable that it be larger than R2. That is, it is desirable that the resistance between both ends of the first breaker 1A in a conductive state is greater than the resistance between both ends of each second breaker 1B in a conductive state. In such a current interrupting device 100, the detection accuracy of the operation of each second breaker 1B can be easily improved. Further, since the resistance between both ends of each second breaker 1B in the conductive state is smaller than the resistance between both ends of the first breaker 1A in the conductive state, the initial state shown in FIG. 8 and the resistance in FIG. In a state where some of the second breakers 1B are operating as shown, the resistance value of the current interrupting device 100 is suppressed, and it becomes possible to increase the charging/discharging current. Note that if the second breaker 1B is configured with only a single second breaker 1B1, the resistance R3 between both ends of the first breaker 1A when it is in a conductive state is equal to the resistance R3 between both ends when the second breaker 1B1 is in a conductive state. It is desirable that the resistance be greater than the resistance R1 between both ends.

In the current interrupting device 100, the resistance between both ends of the first breaker 1A in a conductive state is greater than the resistance between both ends of the at least one second breaker 1B (for example, the second breaker 1B1) in a conductive state. good. In such a current interrupting device 100, the detection accuracy of the operation of the second breaker 1B1 can be easily improved. Moreover, in the initial state as shown in FIG. 8, the resistance value of the current interrupt device 100 is suppressed, and it becomes possible to increase the charging/discharging current.

In general, in the current interrupting device 100 including a plurality of breakers 1, the resistance between both ends of the breaker 1 having the highest operating temperature among the plurality of breakers 1 in the conduction state is the same as that of the other breakers 1 in the conduction state. It is desirable that the resistance be greater than the resistance between both ends at . Even in such a current interrupting device 100, the accuracy of detecting the operation of other breakers can be easily improved. Furthermore, since the resistance between both ends of the other breakers 1 in the conductive state is smaller than the resistance between both ends of the breaker 1, which has the highest operating temperature, in the conductive state, the initial state and the diagram shown in FIG. In a state where some of the breakers 1 are operating as shown in 9, the resistance value of the current interrupting device 100 is suppressed, and it becomes possible to increase the charging/discharging current.

In the current interrupting device 100, it is desirable that the resistance R1 between both ends of the second breaker 1B1 in a conductive state is smaller than the resistance R2 between both ends of the second breaker 1B2 in a conductive state. That is, the resistance between both ends of the second breaker 1B, which has the lowest operating temperature among the plurality of second breakers 1B in the conductive state, is smaller than the resistance between both ends of the other second breakers 1B in the conductive state. is desirable. In such a current interrupting device 100, the accuracy of detecting the operation of other second breakers 1B after the operation of the second breaker 1B having the lowest operating temperature can be easily increased. Furthermore, in the initial state shown in FIG. 8, the resistance value of the current interrupt device 100 is suppressed, so that it is possible to increase the charging/discharging current.

In general, in the current interrupting device 100 including a plurality of breakers 1, the resistance between both ends of the breaker 1 having the lowest operating temperature among the plurality of breakers 1 in the conduction state is the same as that of the other breakers 1 in the conduction state. It is desirable that the resistance be smaller than the resistance across both ends. In such a current interrupting device 100, the accuracy of detecting the operation of other breakers 1 can be easily improved. Moreover, in the initial state as shown in FIG. 8, the resistance value of the current interrupt device 100 is suppressed, and it becomes possible to increase the charging/discharging current.

In the current interrupting device 100, the resistance R1 between both ends of the second breaker 1B1 in a conductive state is smaller than the combined resistance (RR2) between both ends of the second breaker 1B2 and the first breaker 1A in a conductive state. desirable. That is, the resistance between both ends of the second breaker 1B, which has the lowest operating temperature among the plurality of second breakers 1B in the conductive state, is smaller than the combined resistance between both ends of the other breakers 1 in the conductive state. desirable. In such a current interrupting device 100, it is possible to further improve the accuracy of detecting the operation of the other second breakers 1B after the operation of the second breaker 1B having the lowest operating temperature. Furthermore, in the initial state shown in FIG. 8, the resistance value of the current interrupt device 100 is suppressed, so that it is possible to increase the charging/discharging current.

In general, in the current interrupting device 100 including a plurality of breakers 1, the resistance between both ends of the breaker 1 having the lowest operating temperature among the plurality of breakers 1 in the conduction state is the same as that of the other breakers 1 in the conduction state. It is desirable that the resistance be smaller than the combined resistance between both ends. Even in such a current interrupting device 100, it is possible to further improve the accuracy of detecting the operation of other breakers 1 after the breaker 1 with the lowest operating temperature operates. Furthermore, in the initial state shown in FIG. 8, the resistance value of the current interrupt device 100 is suppressed, so that it is possible to increase the charging/discharging current.

In the current interrupting device 100, the resistance between both ends of the second breaker 1B1 in a conductive state is 2% to 201% of the combined resistance between both ends of the second breaker 1B2 and the first breaker 1A in a conductive state. is desirable. That is, the resistance between both ends of the second breaker 1B, which has the lowest operating temperature among the plurality of second breakers 1B in the conductive state, is 2% to 201% of the combined resistance between the both ends of the other breakers 1 in the conductive state. It is desirable that The second breaker 1B, which has the lowest operating temperature, has a resistance between both ends in a conductive state that is 2% or more of the combined resistance between both ends of the other breakers 1 in a conductive state, so that the second breaker 1B has the lowest operating temperature. The detection accuracy of the operation of 1B can be further improved. The second breaker 1B, which has the lowest operating temperature, has a resistance between both ends in a conductive state that is 200% or less of the combined resistance between both ends of the other breakers 1 in a conductive state, so that the second breaker 1B has the lowest operating temperature. The accuracy of detecting the operation of the other second breaker 1B after the operation of the second breaker 1B can be easily increased.

In general, in the current interrupting device 100 including a plurality of breakers 1, the resistance between both ends of the breaker 1 having the lowest operating temperature among the plurality of breakers 1 in the conduction state is the same as that of the other breakers 1 in the conduction state. It is desirable that the resistance is between 2% and 201% of the combined resistance between both ends. Thereby, it is possible to further improve the detection accuracy of the operation of the breaker 1 having the lowest operating temperature, and to easily increase the detection accuracy of the operation of other breakers 1 after the operation of the breaker 1 having the lowest operating temperature.

When the discharge or charging of the secondary battery pack 201 is stopped by the operation of the current interrupting device 100 and the temperature of the heating element decreases, the temperature of each breaker 1 also decreases, and each breaker 1 is set as shown in FIG. 4 or 7. The cut-off state returns to the conductive state shown in FIG. 3 or 6. The temperature at which each breaker 1 returns from the cutoff state to the conduction state is defined as the return temperature. The return temperature is a temperature lower than the operating temperature, and is set for each breaker 1. The return temperature usually has a correlation with the operating temperature, but can be set independently of the operating temperature depending on, for example, the settings of the curvature and elastic modulus of the thermally responsive element 5 and the elastic modulus of the movable piece 4.

FIG. 12 shows the current interrupting device 100 in which the temperature of the heating element has decreased from the state shown in FIG. 11, and the breaker 1Z having the highest return temperature among the plurality of breakers 1 has returned from the cutoff state to the conduction state. There is.

In the current interrupting device 100 including a plurality of breakers 1, the breaker 1Z with the highest return temperature returns first. Assuming that the breaker 1Z with the highest return temperature is the second breaker 1B that does not include the PTC thermistor 6, discharging or charging of the secondary battery pack 201 is restarted with the return of the second breaker 1B. Accordingly, when the heating element generates heat again and reaches the operating temperature of the second breaker 1B, the current interrupting device 100 shifts again to the state shown in FIG. 11. Such a gentle chattering operation is repeated until the power stored in the secondary battery pack 201 is substantially exhausted.

Therefore, in the current interrupting device 100, it is desirable that the breaker 1Z having the highest return temperature among the plurality of breakers 1 is the first breaker 1A. With such a configuration, the electric power stored in the secondary battery pack 201 is consumed by the PTC thermistor 6 of the first breaker 1A and is substantially exhausted, and the temperature of the heating element becomes the return temperature of the first breaker 1A. The interrupting state of the current interrupting device 100 is maintained until the current decreases to . As a result, the above-mentioned chattering operation is suppressed.

In a configuration in which the breaker 1Z with the highest return temperature is the first breaker 1A, the number of second breakers 1B whose operating temperature is higher than the operating temperature of the first breaker 1A is included in the plurality of breakers 1 is 1 or less It may be. Such a second breaker 1B is difficult to design and manufacture, but by eliminating the second breaker 1B, the design and manufacture of the current interrupting device 100 becomes easy.

In the embodiment in which the breaker 1Z with the highest return temperature is the first breaker 1A, the plurality of breakers 1 may include a breaker 1 with an operating temperature lower than the operating temperature of the first breaker 1A with the highest return temperature. In this case, the breaker 1 having an operating temperature lower than the operating temperature of the first breaker 1A having the highest return temperature may be the first breaker 1A or the second breaker 1B. Since such a breaker 1 is easy to design and manufacture, the current interrupting device 100 is also easy to design and manufacture.

In the current interrupting device 100, the plurality of breakers 1 may be composed of the same fixed piece 2 and the same movable piece 4. "Same fixed piece" is intended to be a fixed piece made of substantially the same material and dimensions, and it is sufficient that it is within the allowable range of process tolerance, but higher precision is not required. Not done. Therefore, for example, fixed pieces having the same conduction resistance as single components are the same fixed piece. The same applies to "the same movable piece". In this case, in each breaker 1, the contact resistance between the fixed contact 21 and the movable contact 41 may be different from each other.

In such a current interrupting device 100, parts such as the movable piece 4 and the thermally responsive element 5 that constitute each breaker 1 can be shared, and the cost of the current interrupting device 100 can be reduced.

FIG. 13 shows a charge/discharge control circuit 200 including the current interrupt device 100. The charge/discharge control circuit 200 includes a current interrupt device 100, a secondary battery pack 201, a power supply section 202, a load 203, and a control section 204.

The secondary battery pack 201 is connected in series to the current interrupt device 100. Power supply unit 202 supplies DC power for charging secondary battery pack 201 . The load 203 receives DC power from the secondary battery pack 201. In the charge/discharge control circuit 200 of this embodiment, both the power supply section 202 and the load 203 are connected to the secondary battery pack 201, but the power of either one may be saved. That is, charge/discharge control circuit 200 includes at least one of power supply section 202 and load 203.

The secondary battery pack 201 has internal resistance and generates heat during charging or discharging. Therefore, in the charge/discharge control circuit 200, the secondary battery pack 201 becomes a heat generating element, and the current interrupt device 100 is arranged so that the heat of the secondary battery pack 201 is easily transferred. In particular, it is desirable that the plurality of breakers 1 constituting the current interrupting device 100 be arranged adjacent to the secondary battery pack 201. In a configuration in which a heat transfer body that transfers heat generated by the secondary battery pack 201 is provided, the plurality of breakers 1 may be arranged adjacent to the heat transfer body.

The control unit 204 controls the charging current from the power supply unit 202 or the discharging current to the load 203. The control unit 204 is connected to the

terminals

101 and 102 of the current interrupt device 100. This allows the control unit 204 to detect the resistance at both ends of the current interrupt device 100.

The control unit 204 learns the temperature of the heating element, that is, the secondary battery pack 201, by detecting the resistance at both ends of the current interrupting device 100. Then, the charging current from the power supply unit 202 or the discharging current to the load 203 is controlled according to the temperature of the secondary battery pack 201.

That is, the control unit 204 controls the charging current from the power supply unit 202 or the discharging current to the load 203 based on the resistance at both ends of the current interrupt device 100. For example, when the resistance at both ends of the current interrupt device 100 increases from RR1 to RR2, the control unit 204 controls the power supply unit 202 or the load 203 so that the charging current or discharging current decreases. Thereby, the temperature rise of the secondary battery pack 201 is suppressed.

Further, when the resistance across the current interrupting device 100 increases from RR2 to RR3, the control unit 204 controls the power supply unit 202 or the load 203 so that the charging current or discharging current is further reduced. Thereby, the temperature rise of the secondary battery pack 201 is further suppressed. Even with such control, when the resistance at both ends of the current interrupt device 100 increases from RR3 to RR4, the control unit 204 stops the operation of the power supply unit 202 or the load 203.

In this manner, the control unit 204 controls the power supply unit 202 or the load 203 in stages based on the resistances at both ends of the current interrupt device 100, thereby efficiently controlling the operation of the power supply unit 202 or the load 203.

Although the current interrupting device 100 and the like of the present invention have been described above in detail, the present invention is not limited to the above-described specific embodiments, but can be implemented by changing various aspects. That is, the current interrupting device 100 of the present invention is a current interrupting device 100 that interrupts current according to temperature changes, and includes at least a fixed piece 2 having a fixed contact 21, an elastic part 44 that can be elastically deformed, and a movable contact. 41, the movable piece 4 presses and contacts the movable contact 41 with the fixed contact 21, and the state of the movable piece 4 is changed to conduction where the movable contact 41 contacts the fixed contact 21 by deforming with temperature changes. A plurality of breakers 1 having different operating temperatures at which the state of the movable piece 4 changes from the conductive state to the cut-off state have a thermally responsive element 5 that changes the state from the state to the cutoff state in which the movable contact 41 is separated from the fixed contact 21, It is sufficient if they are connected in parallel.

[Additional notes]
The present invention includes the following aspects.

[Invention 1]
A current interrupting device that interrupts current,
a fixed piece having a fixed contact; a movable piece having an elastic part that can be elastically deformed and a movable contact, the movable piece presses the movable contact against the fixed contact to contact the fixed contact; a thermally responsive element that changes the state of the movable piece from the conductive state in which the movable contact contacts the fixed contact to the disconnected state in which the movable contact is separated from the fixed contact; Multiple breakers with different operating temperatures at which they turn off are connected in parallel.
Current interrupt device.
[Invention 2]
The current interrupting device according to the present invention, wherein the resistance between both ends of at least one of the breakers in the conduction state is different from the resistance between the ends of the other breakers in the conduction state.
[Invention 3]
According to the second aspect of the present invention, the breaker having the highest operating temperature among the plurality of breakers has a resistance between both ends in the conductive state that is larger than a resistance between the ends of the other breakers in the conductive state. Current interrupt device.
[Invention 4]
According to the second aspect of the present invention, the breaker having the lowest operating temperature among the plurality of breakers has a resistance between both ends in the conduction state that is smaller than a resistance between the ends of the other breakers in the conduction state. Current interrupt device.
[Present invention 5]
According to the second aspect of the present invention, a resistance between both ends of the breaker having the lowest operating temperature among the plurality of breakers in the conductive state is smaller than a combined resistance between both ends of the other breakers in the conductive state. current interrupting device.
[Invention 6]
The resistance between the ends of the breaker with the lowest operating temperature among the plurality of breakers in the conductive state is 2% to 201% of the combined resistance between the ends of the other breakers in the conductive state. The current interrupting device according to the second aspect of the present invention.
[Present invention 7]
According to the first aspect of the present invention, the plurality of breakers include one or more first breakers having a positive temperature coefficient thermistor that conducts the fixed piece and the movable piece when the movable piece is in the cutoff state. Current interrupting device.
[Invention 8]
The current interrupting device according to the present invention, wherein the plurality of breakers include one or more second breakers that do not have the positive temperature coefficient thermistor.
[Invention 9]
The current interrupting device according to the present invention, wherein, among the plurality of breakers, the breaker having the highest return temperature at which the return state returns from the cutoff state to the conduction state is the first breaker.
[Invention 10]
The current according to invention 9, wherein the number of the second breaker whose operating temperature is higher than the operating temperature of the first breaker whose return temperature is highest is one or less among the plurality of breakers. Shutoff device.
[Invention 11]
The current interrupting device according to the present invention, wherein the plurality of breakers include the breaker whose operating temperature is lower than the operating temperature of the first breaker whose return temperature is highest.
[Invention 12]
The current interrupting device according to the first aspect of the present invention, wherein the plurality of breakers include the same fixed piece and the same movable piece.
[Invention 13]
The current interrupting device according to any one of Inventions 1 to 12;
a secondary battery pack connected in series to the current interrupting device;
a power supply unit that supplies power to the secondary battery pack or a load that is supplied with power from the secondary battery pack;
A charge/discharge control circuit comprising: a control section that controls a charging current from the power supply section or a discharging current to the load based on a resistance at both ends of the current interrupting device.

1: Breaker 1A: First breaker 1B: Second breaker 1B1: Second breaker 1B2: Second breaker 2: Fixed piece 4: Movable piece 5: Thermal response element 6: Thermistor 21: Fixed contact 41: Movable contact 44: Elastic part 100 : Current interrupting device 200 : Charge/discharge control circuit 201 : Secondary battery pack 202 : Power supply part 203 : Load 204 : Control part

Claims

A current interrupting device that interrupts current,
a fixed piece having a fixed contact; a movable piece having an elastic part that can be elastically deformed and a movable contact, the movable piece presses the movable contact against the fixed contact to contact the fixed contact; a thermally responsive element that changes the state of the movable piece from the conductive state in which the movable contact contacts the fixed contact to the disconnected state in which the movable contact is separated from the fixed contact; Multiple breakers with different operating temperatures at which they turn off are connected in parallel.
Current interrupt device.
The current interrupting device according to claim 1, wherein a resistance between both ends of at least one of the breakers in the conductive state is different from a resistance between both ends of the other breakers in the conductive state.
The breaker according to claim 2, wherein the breaker having the highest operating temperature among the plurality of breakers has a resistance between both ends in the conductive state that is larger than a resistance between the ends of the other breakers in the conductive state. Current interrupt device.
The breaker according to claim 2, wherein the breaker having the lowest operating temperature among the plurality of breakers has a resistance between both ends in the conductive state that is smaller than a resistance between the ends of the other breakers in the conductive state. Current interrupt device.
3. The breaker having the lowest operating temperature among the plurality of breakers has a resistance between both ends in the conductive state that is smaller than a combined resistance between both ends of the other breakers in the conductive state. current interrupting device.
The resistance between the ends of the breaker with the lowest operating temperature among the plurality of breakers in the conductive state is 2% to 201% of the combined resistance between the ends of the other breakers in the conductive state. The current interrupting device according to claim 2.
The plurality of breakers include one or more first breakers having a positive temperature coefficient thermistor that conducts the fixed piece and the movable piece when the movable piece is in the cutoff state. Current interrupt device.
The current interrupting device according to claim 7, wherein the plurality of breakers include one or more second breakers that do not have the positive temperature coefficient thermistor.
The current interrupting device according to claim 8, wherein among the plurality of breakers, the breaker with the highest return temperature at which the return state returns from the cutoff state to the conduction state is the first breaker.
The current according to claim 9, wherein the number of the second breaker whose operating temperature is higher than the operating temperature of the first breaker whose return temperature is highest is one or less among the plurality of breakers. Shutoff device.
The current interrupting device according to claim 10, wherein the plurality of breakers include the breaker whose operating temperature is lower than the operating temperature of the first breaker whose return temperature is highest.
The current interrupting device according to claim 1, wherein the plurality of breakers are composed of the same fixed piece and the same movable piece.
A current interrupting device according to any one of claims 1 to 12,
a secondary battery pack connected in series to the current interrupting device;
a power supply section that supplies power to the secondary battery pack or a load that is supplied with power from the secondary battery pack;
A charge/discharge control circuit comprising: a control section that controls a charging current from the power supply section or a discharging current to the load based on a resistance at both ends of the current interrupting device.